A Tunnel inside a Crater
Craters are large gaps in the ground, similar to tar pits, except they aren't filled with tar. Craters are usually caused by meteors striking the ground. Often at a crater you will find a Diplodocus or Brachiosaurus that you can run on like a bridge. However, if you fall off the diplodocus and land into a large crater, there is commonly an underground tunnel you can crawl into to get out (as well as a lot of eggs to collect). Also, some craters are linked with Volcanoes and can be filled with lava. Large craters usually have a tunnel leading to an exit for the player.
A Small Crater